Chapter 4: Insolation and Temperature

1. Chapter 4: Insolation and Temperature

2. The Impact of Temperature on the Landscape • All living things influenced by temperature • Adaptation to temperature extremes • Temperature affects human-built landscape • Temperature affects inorganic landscape components • Soil and bedrock exposure Figure 4-1a & 4-1b

3. Energy, Heat, and Temperature • Energy: ability to do work • Forms of energy • Kinetic – energy of movement • Chemical, Potential, Nuclear, etc. • Temperature • Heat • Movement of atoms • Temperature: • Measurement of heat • Temperature scales • Celsius • Fahrenheit • Kelvin Figure 4-2

4. Energy, Heat, and Temperature • The Sun • Primary source of energy for Earth’s atmosphere • Properties of Sun • Average size star • Nuclear fusion • Magnitude of Sun’s energy • Energy spreads as it leaves the Sun • Travels through voids in space without loss of energy Figure 4-3

5. Energy, Heat, and Temperature Figure 4-4 • Electromagnetic (EM) energy • EM spectrum • Wavelength • Distance between two wave crests • 3 important areas of EM spectrum • Visible radiation • Ultraviolet radiation • Too short to be seen by the human eye • Infrared radiation • Too short to be seen by the human eye Figure 4-5

6. Energy, Heat, and Temperature • Insolation • Incoming solar radiation • Shortwave energy • Terrestrial Energy • Longwaveenergy • “Earth’s” energy Figure 4-16

7. Basic Heating and Cooling Processes in the Atmosphere • Radiation • When objects emit EM energy • AKA Heat energy emitted from a body • Warmer objects radiate more effectively • Warmer objects emit at shorter wavelengths Figure 4-6

8. Basic Heating and Cooling Processes in the Atmosphere • Absorption • Body absorbs radiation • Good radiator, good absorber • Reflection • Objects repel electromagnetic waves • Opposite of absorption Figure 4-7

9. Basic Heating and Cooling Processes in the Atmosphere • Scattering • Deflection of light waves by molecules and particles • Transmission • Electromagnetic waves pass completely through a medium • Sunsets Figure 4-9

10. Basic Heating and Cooling Processes in the Atmosphere • Greenhouse effect • Some atmospheric gases transmit shortwave radiation, but not Earth’s longwave radiation • Earth radiation held in by atmosphere • Atmospheric blanket Figures 4-11 & 4-12

11. Basic Heating and Cooling Processes in the Atmosphere • Conduction • Transfer of heat energy across a medium • Energy moves from molecule to another one without changing molecular positions • AKA direct heat transfer by contact • Molecules become agitated, then vibrate & collide with cooler molecules, transferring heat energy Figure 4-13

12. Basic Heating and Cooling Processes in the Atmosphere • Convection • Heat transfer by vertical circulation in a moving substance • Vertical convection cell • Warm air gains heat, expands & rises • Cool air loses heat, contracts & sinks • Advection • Horizontal transfer of heat in a moving fluid • AKA wind Figure 4-14

13. Radiation, Conduction & Convection Operating Simultaneously

14. Basic Heating and Cooling Processes in the Atmosphere • Adiabatic Cooling and Warming • Change in pressure & thus temperature of rising or descending air • Adiabatic cooling • Air rises and expands, molecular collisions decrease, so temperature decreases • Adiabatic warming • Air sinks and compresses, collisions increase so temperatures increase Figure 4-15

15. Basic Heating and Cooling Processes in the Atmosphere • Latent heat • Heat released or absorbed during a phase change • AKA “hidden heat” since latent heat is not felt • Evaporation: liquid water is converted to water vapor • Cooling process • Condensation: water vapor is converted to liquid water • Warming process

16. The Heating of the Atmosphere • Balance between shortwave incoming solar radiation & outgoing longwave solar radiation • Albedo • The higher the albedo, the more radiation the object reflects Figure 4-16

17. The Heating of the Atmosphere: Global Energy Budget • Energy in = Energy out Figure 4-17

18. The Heating of the Atmosphere: Global Energy Budget • Earth does not distribute heat evenly through space & time • Cause of weather and climate

19. Variations in Heating by Latitude and Season • Angle of incidence • Angle the Sun’s rays strike Earth’s surface • The higher the angle, the more intense the radiation Figure 4-18

20. Variations in Heating by Latitude and Season • Atmospheric obstructions • Clouds, haze, particulates, etc. decrease insolation Figure 3-4 Figure 4-20

21. Variations in Heating by Latitude and Season • Day length • The longer the day, the more insolation is received Figure 4-19

22. Variations in Heating by Latitude and Season • Latitudinal radiation balance and the world distribution of insolation • Belt of max solar energy that moves through the tropics following the Sun’s direct rays Figure 4-21

23. Land and Water Contrasts • Land heats and cools more rapidly than water due to: • Specific heat • Transmission • Mobility • Evaporative cooling Figure 4-23

24. Land and Water Contrast Implications • Oceans = more moderate climates • Hottest & coldest places on Earth are interiors of continents • N. (land) vs. S. (water) Hemisphere Figure 4-24

25. Mechanisms of Heat Transfer • Need heat transfer to prevent constant warming at tropics & cooling at poles • Circulation patterns in atmosphere and oceans transfer heat

26. Mechanisms of Heat Transfer • 2 mechanisms move heat poleward in both hemispheres, driven by latitudinal imbalance of heat • Atmospheric circulation (Ch 5) • Oceanic circulation • Direct relationship between atmospheric and oceanic circulation • Air blowing over the ocean creates major surface ocean currents • Heat energy stored by oceans affects atmospheric circulation

27. Mechanisms of Heat Transfer • Northern and southern variations • Near N. Hemisphere pole, landmasses lie so close that little flow can enter the Arctic Ocean • In S. Hemisphere, little land mass allows for constant westward belt of ocean circulation called West Wind Drift • Southern Ocean • (AKA the 5th Ocean)

28. Mechanisms of Heat Transfer • Temperature patterns • Poleward currents transfer warm water poleward • Equatorial currents transfer cool water equatorward Figure 4-25

29. Mechanisms of Heat Transfer Figure 4-26 • Rounding out the pattern • NW portions of N. Hemisphere receive cool water from Arctic Ocean • Water pulled away from western coasts of continents = upwelling • Deep ocean circulation • Global conveyor belt • Tied to short-term climate change

30. Vertical Temperature Patterns • Environmental lapse rate • Normal vertical temperature gradient • Average lapse rate • 6.5°C/km or 6.5°C/1000m) • Temperature inversions • Surface inversions • Upper air inversions Figures 4-27 & 4-28

31. Global Temperature Patterns • Global temperature maps • Seasonal extremes • January & July • BROAD understanding of temperature patterns • Isotherm: line connecting points of equal temperature

32. Global Temperature Patterns • Primary controls on global temperature • Altitude • Temperature decreases with altitude • Latitude • Fundamental cause of temperature variation • Temperature with latitude • Land–Water contrasts • Continents have higher summer & lower winter temps than oceans • Ocean currents • Cool currents push isotherms equatorward; warm currents push isotherms poleward Figure 4-29 – average January temperature Figure 4-30 – average July temperature

33. Global Temperature Patterns • Seasonal patterns • Latitudinal shift in isotherms from one season to another • More pronounced over continents than water and over high latitudes than low latitudes Figure 4-31

34. Global Temperature Patterns • Annual temperature range • Difference in average temperature of warmest and coldest months (usually Jan & July) Figure 4-32

35. Global Warming and the Greenhouse Effect • Climate of Earth is becoming warmer, known as global warming • Air temp increases when atmospheric gases trap longwave radiation • Human-enhanced greenhouse effect • Carbon dioxide main culprit • Also methane, nitrous oxide, CFC’s • Intergovermental Panel on Climate Change Figure 4-33

36. Global Warming and the Greenhouse Effect • Relationship between carbon dioxide and temperature Figure 4-35

37. Summary • Temperature affects both living and nonliving aspects of Earth’s landscape • Energy exists in many different forms, but cannot be created or destroyed • Temperature is a measure of the amount of kinetic energy in the molecules of a substance • Temperature is measured on three primary scales • The Sun is the primary source of energy for Earth’s atmosphere • Electromagnetic radiation is classified by wavelength • The Sun emits three important types of electromagnetic radiation: visible, infrared, and ultraviolet • Insolation refers to incoming solar radiation • Radiation is the process by which electromagnetic radiation is emitted by an object • Radiation can undergo several processes, including absorption, reflection, transmission, and scattering • The greenhouse effect makes Earth able to support life

38. Summary • Conduction is the transfer of heat through molecular collision • Convection is a vertical transport of heat in a fluid • Advection is the horizontal transport of heat • Adiabatic cooling and warming processes do not release or absorb heat • The global radiation budget describes the latitudinal distribution of temperature • Land surfaces heat and cool faster than water surfaces • Heat is transferred globally through atmospheric and oceanic circulations • The vertical temperature patterns in the atmosphere help describe vertical circulations • Global warming is the observed warming of the atmosphere • Temperature and carbon dioxide show a close relationship